There will always be a need for new effective alternatives to existing sanitizers and disinfectants as new pathogens emerge and microorganisms develop resistances to existing antimicrobials. In addition, in certain applications, only “green” or non-toxic antimicrobials are desired: for instance, to sanitize food or food contact surfaces, to treat water, or to disinfect environmental surfaces in areas with sensitive populations (e.g., day care centers, hospital intensive care units) that may not be able to tolerate exposure to harsher chemicals. Also, in some current applications, existing antimicrobials have limited efficacy such as in situations in which the antimicrobial is exposed to high levels of organic material.
Natural antimicrobials from plants are one such possible alternative. Plants produce antimicrobials in various areas such as in the roots, leaves, bark, and stem, coinciding with the various assaults that the plant might encounter in the environment (Burt 2004). Numerous plant extracts, essential oils, and their components have significant antimicrobial properties (Didry et al., 1994; Friedman et al., 2002; Olasupo et al., 2003; Singh et al., 2003; Gupta and Ravishankar 2005; Knowles et al., 2005; Peñalver et al. 2005; Uhart et al., 2006; Callaway et al., 2008; Nannapaneni et al., 2008; Ravishankar et al., 2008; Ravishankar et al., 2009; Ravishankar et al., 2010). Many plant antimicrobials are used and are often found in the average household kitchen cabinet. Such common and longstanding usage has earned these antimicrobials the label of Generally Regarded As Safe (GRAS) compounds (Dillon 1999; Ress et al., 2003; Adams et al., 2004; Knowles et al., 2005). In addition, these compounds are likely not affected by the presence of organics and therefore may be easier to maintain at the appropriate effective concentrations than antimicrobials such as chlorine (Dillon 1999; Silvestry-Rodriguez et al., 2007a; Matthews 2009).